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A Crafty Disguise February 6, 2008

Posted by Mrs Weird Scientist in Animals, Evolution, Insects, Tough Stuff.
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A very tricky parasite has recently been discovered. What makes it so sneaky? After infecting a certain species of ant known as Cephalotes atratus, the parasitic nematode triggers changes in the ant’s abdomen, which then becomes red and swells. This bulging, red appearance resembles a berry. Birds who feed on this type of fruit mistake the ant for a berry, swoop in and gulp! The bird swallows the ant, which allows the parasite to now infect the bird. Once birds are infected, the parasite can spread through the birds’ feces. In a bizarre circle of events, the ants round off the infectious cycle by gathering up the birds’ droppings so that they – along with their young – can feed off the feces. Smart parasite! It manages to sustain itself through the host ant so it can infect the unsuspecting birds – who think they’re about to eat a juicy, luscious berry!

Ants

Credit: Steve Yanoviak of the University of Arkansas. Check out the normal worker ant in the top picture and then compare it to the picture below it, which shows an ant infected with a parasitic nematode. That is one seriously red abdomen! It will be the doom of the ant when a bird mistakes it for a yummy, red berry.

Welcome To The Amazon

This peculiar cycle was observed in the tropical forests in the Amazon and Central America. Robert Dudley of the University of California – Berkeley described his surprise at finding such an intelligent series of events:

It’s just crazy that something as dumb as a nematode can manipulate its host’s exterior morphology and behavior in ways sufficient to convince a clever bird to facilitate transmission of the nematode.

The discovery itself was a chance one as Dudley, Yanoviak and Michael Caspari of the University of Oklahoma were observing a gliding species of ant. They noticed that some of the colony members had bright, red abdomens. Normally, birds don’t even eat ants – partly because of their yucky chemical taste. Yanoviak had some cool things to say about this fascinating discovery:

It’s phenomenal that these nematodes actually turn the ants bright red and that they look so much like the fruits in the forest canopy.

The full article describing the fruit mimicry will be published later this year in the journal American Naturalist. It might be worth a wee read to get the entire scoop on this amazing discovery. Also, research like this doesn’t go without funding – it was partially supported by the National Geographic Society, Amazon Conservation Association and the BBC Natural History Unit.

Evolution

I’m absolutely amazed at the findings. It’s incredible that something as seemingly simple as a nematode can manipulate the ants in such a successful way. It just goes to show that whether a creature is simple or complex, evolution can be one smart cookie!

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Dinosaur Breath Tells Secrets November 14, 2007

Posted by Mrs Weird Scientist in Animals, Dinosaurs, Environment, Evolution, Think About It.
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Sssssssh. Believe it or not, dinosaur breath can tell us quite a bit about how dinosaurs evolved and what sort of life they experienced. Led by Dr Jonathan Codd, a team at the University of Manchester in the United Kingdom did some investigating and found that theropod dinosaurs had respiratory systems that were similar to modern marine birds and wildfowl. If you’re not too well versed in dinosaur lingo, then ‘theropod’ might be a new word for you. Theropods were the quick-moving, massive, mostly carnivorous dinosaurs that roamed Earth. They also had powerful legs and clawed hands. The results of the investigation are really cool because they give us some insight into how dinosaurs actually breathed. The full details of the research were published in the Proceedings of the Royal Society B: Biological Sciences.

Dinosaurs

Credit: Jonathan Codd of the University of Manchester. Let the battle begin! This picture shows a Protoceraptops fighting it out with a Velociraptor mongoliensis. The lengthy uncinate processes can be seen on the rib cage of the velociraptor.

I Knew That

There already are studies showing that dinosaurs were the direct ancestors of birds but scientists are still trying to find out to what extent anatomical features are shared. So, even if you already knew that there were a bunch of avian characteristics in dinosaurs, there is still lots to learn as new features are identified – like dinosaur breathing structures! Much of what we know is built upon heaps of studies. We basically keep adding new information to the pot – sometimes this information makes us say ‘Wow, the old idea was way off!’ Other times it extends what we know by explaining it in more detail. In this case, we’re simply adding new information to the mix!

Breathe In, Breathe Out

Inhale and exhale! We already know that birds – especially diving birds – have really well functioning respiratory systems. In fact, they have one of the most efficient systems of vertebrates. Why so efficient? It’s because they need loads of oxygen to keep up their constant flying. They have special breathing structures called uncinate processes. After looking at fossilized remains of dinosaurs and birds, the researchers found that uncinate processes were also present in dinosaurs. Codd talked about how dinosaur breathing is more specialized than was first believed:

Our work on modern birds has shown that the way these animals breathe is more complex than originally thought. The uncinate processes are small bones that act as levers to move the ribs and sternum during breathing. Interestingly, these structures are different lengths in different birds – they are shortest in running birds, intermediate in flying birds and longest in diving birds.

The dinosaurs we studied from the fossil record had long uncinate processes similar in structure to those of diving birds. This suggests both dinosaurs and diving birds need longer lever arms to help them breathe.

Finding these structures in modern birds and their extinct dinosaur ancestors suggests that these running dinosaurs had an efficient respiratory system and supports the theory that they were highly active animals that could run relatively quickly when pursuing their prey.

Ultimately, the uncinate processes allowed the dinosaurs to move around very fast, which meant they could rapidly capture prey. Right now though, you’re probably breathing a sigh of relief that this article wasn’t about bad dinosaur breath! With all the raw meat they ate, I have a feeling it would have been really gross. Yuck!

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